The C-terminal domain of the transcriptional regulator BldD from Streptomyces coelicolor A3(2) constitutes a novel fold of winged-helix domains

BldD regulates transcription of key developmental genes in Streptomyces coelicolor. While the N-terminal domain is responsible for both dimerization and DNA binding, the structural and functional roles of the C-terminal domain (CTD) remain largely unexplored. Here, the solution structure of the BldD-CTD shows a novel winged-helix domain fold not compatible with DNA binding, due to the negatively charged surface and presence of an additional helix. Meanwhile, a small elongated groove with conserved hydrophobic patches surrounded by charged residues suggests that the BldD-CTD could be involved in protein-protein interactions that provide transcriptional regulation. Proteins 2014; 82:1093-1098. (c) 2013 Wiley Periodicals, Inc.